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/*
a permutation of a set is, loosely speaking, an arrangement of its members into a sequence or linear order, or if the set is already ordered, a rearrangement of its elements.
The word "permutation" also refers to the act or process of changing the linear order of an ordered set
More at : https://en.wikipedia.org/wiki/Permutation
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*/
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const createPermutations = ( str ) => {
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// convert string to array
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const arr = str . split ( '' )
// get array length
const strLen = arr . length
// this will hold all the permutations
const perms = [ ]
let rest
let picked
let restPerms
let next
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// if strLen is zero, return the same string
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if ( strLen === 0 ) {
return [ str ]
}
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// loop to the length to get all permutations
for ( let i = 0 ; i < strLen ; i ++ ) {
rest = Object . create ( arr )
picked = rest . splice ( i , 1 )
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restPerms = createPermutations ( rest . join ( '' ) )
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for ( let j = 0 , jLen = restPerms . length ; j < jLen ; j ++ ) {
next = picked . concat ( restPerms [ j ] )
perms . push ( next . join ( '' ) )
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}
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}
return perms
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}
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export { createPermutations }
